Boiler



Aug. 27, 1 946. A. DRUMMOND 2,406,673

BOILER Filed April 19 1944 3 Sheets-Sheet 1 lMINI f "UI/pl' WWII N MIU Ml IME ATTE/YE'Y llllllllllllllllllllllllllllllllllll ...5l

3 Sheets-,Sheet 2 A. DRUMMOND BOILER Fi1ed Apri1 19, `1944 v Aug. 27, 1946.

Aug. 27, 1946. y A, DRUMMOND 2,406,673

BoILER FiledApril 19, 1944 f s sheets-sheet 5 ATTQB'YEYS Patented Aug. 27," 1946 `BOILER Andrew Drummond, St. George, Staten Island, N. Y., assignor to Lehigh Valley Coal Sales N. Y., a corporation of Company, New York New Jersey Application April 19, 1944, Serial No. 531,753

7 Claims. (Cl. 1229-158) This invention relates vto improvements in boiler or furnace construction, particularly to improvements in units of the type suitable'for domestic'or home heating by means-of steam or hot water. However its features are also applicable to installations larger than those of the home heating type. Y

In my Patent 2,228,757 I have disclosed a boiler construction of a type particularly suitable for use in the heating of homes by means of steam or hot water. That construction is characterized by a lower combustion chamber, and by an upper or hopper portion forming with the combustion `zone a boiler and fuel storage assembly arranged in hourglass fashion. YThus, the ar-k rangement includes a constricted neck portion providing a 'throat or passageway for the transfer of coal between hopper portion and combustion chamber. Each of the two elements of` this construction, the hopper and the combustion chamber, are arranged in conical or pyramidal form, the hopper Walls in the lower part being inclined to the horizontal at an angleapproximately that of the angle of repose of thekk fuel.

In the construction disclosed in my patent there is also provided a secondaryV combustion chamber which surrounds the above mentioned throat,

and is of substantially triangular vertical cross sectionv and wherein gases evolved from the coal or other fuel utilized are burned. This secondary combustion chamber is connected with the primary combustion chamber by means of tubular conduits, and with the flue gas header leading to the chimney by means of a number of conduits which are also tubular in form and which serve to carry out the products of combustion formed in both combustion chambers.

While the hourglass construction with its surrounding secondary combustion chamber of tri-` angular cross section is very satisfactory in many installations, and while the principles ofits operation are admirably adapted for the heating of hot Water or the generation of steam by vmeans of coal or other solid fuel, especially in installations of the domestic type, the necessity for providing four reentrant portions to give the hourglass shape hasV increased the cost of manufacturing units of this type. Moreover, the secondary combustion chamber of triangular cross section is so shaped as to render it and-related parts very diflicult 'of'construction and assembly. It complicates particularly the problem of forming a firm 'and leak-proof connection between this chamber'andthe ends of theftubes which provide ,the conduits `for the escape of theproducts of combustion from the secondary combustion chamber to the chimney. A simple and more effective way of applying such tubes is to insertV them in place in the boiler construction, and thenroll over or crimp their end portions in order to Yhold the tubes in position and form the desired tightjoint. Because of the limited space provided in the secondary combustion chamber it is difficult, if possible at all, to roll overfthe endsrof the tubes at the point where they enter that chamber when the construction disclosed in my patent is utilized.

In the construction shown in my patent I have also provided a number of ducts arranged in tubular form to provide communication between the .primary combustion chamber in the lower half of .the hourglassrconstruction and the secondarycombustion chamber. While these tubes perform their Afunction very satisfactorily, they add to the cost of the construction and they complicate the problem of cleaning the boiler. These are, of course, factors of considerable importance, especially where the units are intended for home heating. purposes.

I havek now devised a new and improved boiler or furnace construction of the general type shown in my issued patent, which construction involves, however, theV simplification of that structure to the end thatthe boilers may be manufactured more readily and at lower cost than previously possible. Accordingly, it is a main and primary object of this invention tov simplify the boiler or furnace construction shown in my issued patent, at the same Atime retaining its advantages without modifying the principles under which it operates, tothe end that the units may be manufactured and maintained more economically than heretofore possible. f

Another object of this invention involves the elimination `of the four reentrant portions of my formerv construction, these reentrant portions providing an hourglass shape, and their replacement by a single reentrant portion without, however, surrendering any ofthe advantages of operationinherent in the arrangement shown in my patent.

A third object of my invention involves modifying the .conformation of the secondary combustion chamberv wherein the fuel gases are burned before their passagel to the chimney so that fthe endless, `triangularly cross-sectioned combustion chamber surrounding the throat of my former Vconstruction is replaced by onewhich is straight andzgenerally trapezoidal in cross section.- By this changethere is provided adequate room for the rolling in of the ends of the fire tubes forming the du'cts communicating with the nue gas header. By changing the cross-sectional conformation of this secondary combustion chamber and its shape in plan I am also able to secure more satisfactory combustion of the gases in this chamber than previously possible with the triangularly shaped member shown in my issued patent and the cleaning problem is greatly simplified.

A fourth object of this invention involves the simplication of the connection between the main combustion chamber and the secondary combustion chamber whereby the series of tubes previously 'utilized is replaced by a single large opening, thus permitting free passage of the gases between the combustion chambers. This change not only eliminates the replacement problem present when such tubesy are used, but cleaning is also simplified, since ash or dirt readily falls back into the main combustion chamber and does not remain in the connecting conduits.

.A fifth object of my invention involves the simpliiication of the upper storage hopper construction wherein a single boiler plate and not the water space of the boiler as in my issued patent now formsthe sides of the hopper. Thus, the only heated surface coming in contact with the fuel in reserve is the sloping bottom I1a. These and still other objects of this invention will be apparent from the ensuing disclosure of certain preferred embodiments thereof.

My invention is best illustrated with reference to the annexed drawings which show a preferred embodiment of a boiler or furnace construction incorporating it. While this description is given in some detail it should be regarded as illustra'- tive, keeping in mind that the inventive Principles thereof may be embodied in other types of construction than that illustrated.

In the annexed drawings,

Figure 1 is an elevational view of the improved boiler as seen from the rear.

Figure 2 is a central, longitudinal, vertical section through the boiler taken on line 2-2 of Figure 1 looking in the direction of the arrows.

Figure 3 is a transverse vertical section through the boiler taken on line 3-3 of Figure 2. As shown, this section is taken along a bent line in order that the interior features of the boiler construction may be more adequately illustrated.

Referring now to the drawings, my improved boiler or furnace construction may be said to consist of three principal portions: a base 1 forming the ash pit of the unit; a main boiler portion 8; and a magazine or storage portion 9. The water space of the boiler is located between an outer wall 8a and an inner wall 8b. One side of the inner wall is reentrant and shaped so as to form a combustion chamber II and a fuel hopper I2. The base is a box-like member which may be formed of sheet metal or cast iron or steel, suitably bent and welded or otherwise fastened to provide a sturdy supporting structure. The magazine portion 9 may be of sufficient capacity to retain an adequate supply of solid fuel to enable the operation of the boiler continuously over an extended period, twenty four hours or longer.

Turning rstto the main boiler section 8, this includes the combustion chamber I l in whichvthe fuel is ignited and permitted to burn, and the fuel supply member or hopper I2 in open communication with the combustion chamber, the fuel being delivered to the latter from the hopper I2 through the constricted portion or throat I4. The hori- Vzontal cross-sectional area of thisI restricted throat portion I4 may advantageously be less than one-quarter of the horizontal cross-sectional area of the lower portion of combustion chamber II. As shown in Figure 2, both the fuel storage hopper and the main portion of the combustion chamber are roughly in the form of wedges of generally triangular cross section meeting at the throat I4.

At the lower portion of the combustion chamber there are provided a plurality of grate bars I 5 on which the fuel is supported during burning. The angle that the wall I1 of the combustion chamber I I, and its continuation up to the throat, forms with the horizontal is preferably approximately that of the angle of repose of the solid fuel used,

thereby insuring that the fuel will entirely fill said combustion chamber and spread out more or less uniformly over the entire area of the lower portion of the combustion chamber so that there will be substantially no air or gas space above the fuel within the combustion. chamber and the fuel will not tend to enter the secondary combustion chamber to be hereinafter described. As shown, the hopper I2 is provided with sloping bottom I1a, which is the only heated surface coming in contact with the fuel in the hopper.

Surrounding the combustion chamber II and the throat I4, there is provided, as shown, a water jacket or compartment I9 forming the water space of the boiler in which water is heated by means of the heat developed in primary combustion chamber II and in secondary combustion chamber 29. As shown, this water space I9 is a rectangular shell in form having a relatively narrow width at three sides of the unit designated by numerals 2l, this Width increasing at the fourth side and surrounding the flue tubes 22 to the width shown at the right hand end of Figure 2. The Water space also partially surrounds the secondary combustion chamber 29, as shown at 23. As shown. the water space I9 is normally filled with Water to about the level indicated.

As shown particularly in Figs. 2 and 3, the inclined wall of the upper hopper section is supported by the usual stay bolts 24 and 25. The lower end of the water space I9 is stayed by means of stay bolts 26 running in one direction and stay bolts 21 running in the other direction. .The primary combustion chamber is supported transversely by means of stay bolts 29, while stay bolts 3l support the narrower sections 2| of the boiler compartment I9 as shown, for example, at the left hand end in Figure 2 and in Figure 3.

The primary combustion chamber II is in direct communication with the secondary combustion chamber 20 through opening 36. As shown, this secondary combustion chamber has a trapezoidal shape in transverse cross section and extends across the boiler compartment. ln this combustion chamber gases distilled from the fuel, as well as gases resulting from incomplete combustion in the primary combustion chamber, are burned. On either side of the unit there are provided doors 31 shown in Figures 1 and 3, by which access may be had through the trapezoidal openings 33 to the secondary combustion chamber 20. Y

The secondary combustion chamber 20 is connected with the flue gas header 40 by means of flue tubes 22. As shown (see Fig. 3) these tubes are arranged across the boiler unit and extend horizontally in a number of rows, the position of the tubes being staggered in successive rows. By means'v of the doors 31 providing access to the secondary. combustion chamber-2 through openings 38 it is possible to insert a tool for the purpose of rolling over the ends of tubes 22 to hold them firmly in place and form a tight joint. Sufficient room for the insertion of a suitable tool is readily provided by the large cross-sectional area, trapezoidal in shape, of the secondary combustion chamber 20. A tool may Aalso be inserted through clean-out Ydoor 43 of flue gas header 40 to permit rolling over the outer ends o-f tubes 22, thus permitting firm securement of these tubes in place in the boiler and permitting their ready replacement in the event they ybecome burned out. Tubes 22 serve'not only to draw olf the products of combustion developed in combustion chamber 20, but also the products of combustion developed in primary combustion chamber i i, the primary and secondary combustion chambers communicating, as previously noted, through the opening 36.

The boiler is also provided at its upper portion with a fuel charging opening 41 closed normally by hinged cover 48. Access to the upper surfaces of the grate bars I5 may be afforded through the door 49 but its main purpose is to provide for the admission of air through the sliding grid 49a (if desired) in order to offset the increased resistance of the fuel bed at its greatest depth to the normal penetration of air through the grate. By providing additional air in this manner through thesliding grid 49a, a bright spot normally present on the lower surface of the fuel bed and necessary to ignite the gases distilled from the green fuel as it falls downwards from the upper. storage hopper, may be extended upwards along the surface of the fuel bed all the way to the throat in order to accelerate combustion. There is provide grate shaker mechanism including the handle 5I which serves through mechanism not shown to shake the grate bars, thereby permitting the ashes to drop into the ash retainment section 1. Access thereto for the removal of ashes is provided through ash door 52.

The draft regulating arrangement is substantially identical with ythat shown in my Patent 2,228,758 and includes draft damper 54, normally closed when air is permitted to travel directly through the burning fuel on grate bars I5. This draft damper is positioned in conduit 55 communicating with flue gas header 40 which, in turn, leads to the chimney (not shown) through flue duct 56.

Asshown particularly in Figures 2 and 3, the water in vthe boiler section I9 surrounds the ue tubes 22, thereby deriving heat from the burned gases as they travel from the secondary combustion chamber 20 to the flue gas header 40. There is also positioned in the upper portion of this boiler section, above the flue tubes 22, a series of U-shaped pipes 58 which are connected to a header 59. These pipes serve to hold Water for heating, this hot water supply being then Withdrawn through header 59. This feature is particularly important when the boiler is designed for domestic or home use as it provides a ready supply of hot water While the heating system is in operation,

The boiler is lagged by the usual insulation, designated generally as 6|. It is also provided with the usual relief valve 62 to permit the escape of excessive steam pressure. To provide for the withdrawal of steam from the boiler section I9, and to permit the return of the condensate thereto, there are provided one or more ports 63 above the water level and one or more ports 64 below the water level. .Provision forsupplying vadditional water whenever desired, and for draining the boiler, may be made in connection with the pipes leading to one or both of the ports 64. Any of these ports which are not used may be provided with suitable closures, not shown, as usual in boilers. These or other passages communicating with the interior of the boiler may be used'V for the 'introduction of auxiliary devices, such as pressure gauges or temperature recording devices, in accordance with practices well un derstodiny the boiler art. As shown most clearly in Figure 1, there is also provided a number of draw-off cocks and water level indicators of a type usual in boilers, these being indicated generally by the numeral B5. Also included is a sight glass 66 of any usual type for observing the level of water in the boiler, valves 6l being provided for controlling access of liquid thereto.

Any appropriate means may be provided for regulating damper 54. In the construction shown there is provided damper operating rod 68 extending to either side of the boiler, this rod being adapted for remote operation by mechanism of any suitable type not shown.

,While a preferred form of the invention has been described in considerable detail vit will be understgod that various changes may be made in the construction or in the arrangements of the various parts thereof without departing from the general form of the invention. While my invention has been described with particular reference to a boiler for the generation of steam or for heating water, certain features -thereof are applicable to other types of furnaces, for example, to those of the hot air type, and it is my intention that my invention shall be construed to cover such modifications. The scope of the invention is therefore not to be restricted to the preferred form and to the detailed description thereof given as illustrative, but is to be construed in accordance with the appended claims,

I claim:

l. In a boiler of the class described, an outer wall structure; inner walls within said outer wall structure, one of said inner walls being provided with a reentrant portion forming with said outer walls a primary combustion chamber of substantially wedge-shaped form and a superposed wedge-shaped fuel storage hopper, said primary combustion chamber and said fuel storage hopper being connected for the passage of fuel therebetween at a restricted throat portion, said relentrant portion providing also a roof for said combustion chamber inclined at a substantial angle and being formed to provide a secondary combustion chamber, said secondary combustion chamber communicating with said primary combustion chamber whereby the products of the combustion may pass therebetween; means providing an additional supply of air to the fuel in said primary combustion chamber whereby incandescence thereof may be controlled; and flue means including tube means providing communication between said secondary combustion chamber and a chimney, said outer Wall structure and said inner walls being adapted to retain water around at least portions of said combustion chambers.

2. A boiler according to claim 1 in which the secondary combustion chamber is of substantially trapezoidal cross section.

3. A boiler according to claim 1 in which the tube means comprises a plurality of spaced and substantially parallel tubes.

4. A boiler according to claim 1 in which the restricted throat portion has a horizontal crosssectional area less than one-quarter of the corresponding area of the lower portion of the primary combustion chamber and in which the roof for the primary combustion chamber is inclined with respect to a horizontal plane at an angle at least equal to the angle of repose of the fuel.

5. In a boiler of the class described, an outer wall structure; inner walls within said outer Wall structure, one of said inner walls being provided with a reentrant portion forming with said outer walls a primary combustion chamber of substantially wedge-shaped form and a superposed substantially wedge-shaped fuel storage hopper, said primary combustion chamber and said fuel storage hop-per being connected for the passage of fuel therebetween by a restricted throat portion, said reentrant portion providing a roof for said combustion chamber inclined at a substantial angle and also being formed to provide a sec ondary combustion chamber extending across the interior of the boiler, said secondary combustion chamber communicating with said primary combustion chamber whereby the products of combustion may pass therebetween; and flue means including a plurality of tubes providing communication between said secondary combustion chamber and a chimney, said secondary combustion chamber being suiciently large to permit the introduction of an edge-turning tool whereby the edge portions of said tubes positioned in said secondary combustion chamber may be turned over to form a tight joint and retain said tubes in place, said outer wall structure and said inner walls being adapted to retain water around at least portions of said chambers.

6. A boiler according to claim 5 in which the restricted throat Yportion has a horizontal crossd sectional area less than one-quarter of the corresponding area of the lower portion of the pri-A mary combustion chamber and in which the roof for, the primary combustion chamber/is inclined with respect to a horizontal plane at an angle at least equal to the angle of repose of the fuel.

'7. A boiler. of the class described comprising an outer wall structure, inner. walls within said outer wall structure arranged to provide within the latter a primary combustion chamber, a secondary combustion chamber in direct communication with said primary combustion chamber and closelyadjacent thereto, and a fuel storage hopper superposed above said combustion chambers, a substantially horizontal grate at the bottom of said primary combustion chamber, said primary combustion chamber and said fuel storager hopperhaving at least two vertical walls in substantial alinement and being connected for the passage of fuel therebetween at a restricted throat portion-provided by the reentrant formation of certain of the inner walls, said certain ofthe inner Walls forming an inclined bottom for said fuel storage hopper adapted to feed solid fuel therefrom by gravity, said certain of the inner walls also being s-o formed and arranged as to provide a relatively large primary combustion chamber adapted to be kept constantly filled by gravity flow of fuel from said hopper and a relatively small secondary combustion chamber arranged to receive the gases from said primary chamber, and flue means including tubes providing communication between said secondary combustion chamber and a chimney, said outer wall structure and said inner walls being adapted to retain water around at least portions of said combustion chambers and said tubes.

ANDREW DRUMMOND. 

